PH 7.0 was selected in the all experiments, because both natural water and not only has the TCNM suspension a similar pH value, but also the different pH values have little effect on the degradation rate of TCNM.
Effect of Nitrate Ion on the Photodegradation of TCNM. Nitrate ion is a component of natural water because of their important role in the fate and transport of many pollutants.
Effect of Chloride Ion on the Photodegradation of TCNM. In nature, chlorine is found primarily as the chloride ion, a component of the salt that is deposited in the earth or dissolved in the oceans.
Effect of Humic Acid on the Photodegradation of TCNM. Humic acid is a ubiquitous and heterogenous group of natural organic compounds because of their important role in the fate and transport of many pollutants.
Based on the observed photoproducts and reaction kinetics and information available in the relative literatures [21, 25, 26], the photodegradation of TCNM might undergo an n-[PI] * transition to the diradical A, followed by Nesmeyanov rearrangement to B, ring-closure to the oxazirane N-oxide C, and decomposition to CO[Cl.sub.2] and NOCl (Figure 8).
While others researchers thought that TCNM was photodegradated by [sup.*]OH under UV, [sup.*]OH can oxidatively degrade TCNM rapidly, which may react through the following two paths [27-29]:
TCNM + [sup.*]OH [right arrow] C[Cl.sub.3]OH + [sup.*]N[O.sub.2] (4)
TCNM + [sup.*]OH [right arrow] [sup.*]C[Cl.sub.3] + ONOOH (5)
Hydroxyl radical degrades TCNM through reactions (4) and (5) because it is electrophilic reagent that is more likely to react with the nitrogen atom of the nitro in TCNM.